Case Presentation

1
Case Presentation

• JB is a previously healthy 49 year old white male
• He cut his arm on a clean piece of aluminum that
  he was installing around a window frame at a car
  dealership in late April
• He received local care only and the wound
  appeared to heal and crust over
• Approximately 1 week thereafter, however, the
  wound began to develop erythema, swelling,
  pain Ffevers or chills then

2
Case Presentation

• The wound then spontaneously opened and purulent
  material began to drain from it
• The swelling and erythema began to spread up the
  arm and down over the wrist and hand
• There was pain with movement of the arm
• Pt. presented to a local ED and ultimately came
  to WFUBMC ED

3
Case Presentation

• Afebrile upon presentation (T98.9)
• Seen by ortho and thought to have a R forearm
  abscess
• ESR 77 CRP 29.99
• Plain films ? marked soft tissue swelling but no
  evidence of osteo, fracture, or foreign body
• Underwent I D cultures submitted

4
Case Presentation

• Treated with cefazolin, elevation, W?D dressings,
  with a slow response
• Culture data then forthcoming
• ID consult obtained

5
Culture Results
6
ID Insights

• R forearm soft tissue infection/abscess secondary
  to MRSA no evidence of bony involvement s/p
  ID
• Of interest that the infection is
  community-acquired
• Change cefazolin to vancomycin cont. tx for 2
  weeks
• Further history revealed that pts wife has CHF
  and was hospitalized at WFUBMC 1 year ago, but
  the patient himself had no h/o health care
  facility contact

7
A FEW WORDS ABOUT COMMUNITY-ACQUIRED MRSA
8

• Salgado CD, BM Farr, and DP Calfee.
  Community-Acquired Methicillin-Resistant
  Staphylococcus aureus A Meta-Analysis of
  Prevalence and Risk Factors. CID200336-131-9.
• 57 studies were included in the meta-analysis to
  attempt to determine the prevalence of health
  care-associated RFs among community members with
  MRSA and the prevalence of MRSA colonization
  among healthy persons with no RFs for acquisition

9
Nosocomial MRSA

• The rate of methicillin resistance among S.A.
  strains causing nosocomial infections in ICU
  patients has approached 50 in US health care
  facilities
• Risk factors for nosocomial acquisition of MRSA
  include prolonged hospitalization, care in an
  ICU, prolonged antimicrobial therapy, surgical
  procedures, close proximity to a pt. infected
  or colonized

10
So what about MRSA which is community-acquired?

• The 1999 report of 4 pediatric deaths resulting
  from CA-MRSA infection resulted in greatly
  increased interest in this organism and raised
  important questions about the prevalence and
  origin of CA-MRSA
• A standard definition has not yet been created
  for CA-MRSA
• The Salgado et al paper states that at least 8
  different definitions have been used to classify
  MRSA infections as community-acquired

11
How does MRSA become designated as community
acquired?

• Most studies of hospitalized patients have used a
  time-based approach to distinguish between
  community-acquired and nosocomial infections
• e.g. infections present upon admission or dxed
  w/in 48-72 h are considered community-acquired
• This approach has limited utility in the
  evaluation of S.A. infections, as MRSA
  colonization can persist for months to years

12
CA-MRSA- a misnomer?

• The majority of colonized patients remain
  completely asymptomatic
• The commonly-used term CA-MRSA implies that it
  is known that the organism was acquired in the
  community
• It appears that this term is often used to refer
  to detection of infection or colonization in the
  community, rather than to actual acquisition of
  MRSA in the community

13
CA-MRSA- a misnomer?

• These investigators found that when even minimal
  RF assessment was done, at least 85 of hospital
  pts. who met the time-based definition for
  CA-MRSA and 48 of healthy community members
  found to be colonized w/ MRSA had gt or 1 health
  care-associated RF for acquisition
• This suggests that the prevalence of MRSA among
  persons w/o typical RF remains very low (.24)
  and that most MRSA colonization and infection
  develops among those who have health
  care-associated RFs including contact w/ others
  who have such risks

14
CA-MRSA- a misnomer?

• The term community-onset MRSA (CO-MRSA) which
  describes the patients location at the time of
  identification of MRSA, would be more technically
  correct than CA-MRSA
• When a patient w/ nosocomially-acquired MRSA
  spreads the organism to members of his household
  or community, this should not be called
  community acquisition

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Conclusion of Salgado paper

• Major RFs for CO-MRSA appear to be those already
  identified as RFs for nosocomial MRSA, which
  suggests that the increase in CO-MRSA among
  non-hospitalized patients is, in large part, due
  to the introduction of health care-associated
  strains into the community

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MRSA Trivia

• Methicillin was introduced in 1959
• Outbreaks of MRSA infections occurred in Europe
  in the early 1960s
• The distribution of MRSA is now worldwide
• The presence of the mec gene is an absolute
  requirement for S.A. to express methicillin
  resistance
• It is absent from susceptible and present in all
  resistant strains

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A Cheerful Thought

• In the end the microbes will win.
• David Stevens, M.D.